JP2600715B2 - Robot servo control method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a servo control method for driving and controlling an operating part such as an arm in a robot,
The present invention relates to a servo control method suitable for use in an industrial robot such as a coating robot (for example, a painting robot) having a spray gun that is driven at a constant speed and controlled to be turned on / off at the time of positioning for outputting a movement command or the like to itself. Things.

2. Description of the Related Art In general, as an apparatus for controlling an operation part (an arm, a spray gun, or the like) of an industrial robot, for example, a coating robot, there is an apparatus as shown in FIG. 5 (block configuration diagram). In FIG. 5, reference numeral 1 denotes a CP for setting a control cycle, performing various arithmetic processes, creating control commands, and the like.
U and 2 indicate the path of the spray gun 7b of the coating robot 7, the positioning time for outputting the operation command for the spray gun 7b, and the ON / OFF to be performed at that time.
A memory for storing the OFF control operation and the like, 3 is a servo control unit, which receives a control command from the CPU 1 every predetermined control cycle,
It controls a servo motor (drive unit) (not shown) for driving the arm unit 7a, the spray gun 7b, and the like, which are the operation parts of the robot 7.

Reference numeral 4 denotes an input / output interface unit for performing on / off control of the spray gun 7b, and reference numeral 5 denotes an operation switch interface unit for a teaching board 6 used when teaching the robot 7.

FIG. 6 is a diagram showing specific contents (an example of an operation command for the robot 7 taught from the teaching board 6) stored in the memory 2, and the contents are shown by the robot 7 (spray gun 7b). After moving from the position “0” to the position “83” (positioning command position), and outputting an operation command signal “1” (for example, an injection ON / OFF command from the spray gun 7b) at this position, the position “ It indicates that control is performed to move to 125 ".

The coating robot 7 has a spray gun
When painting with 7b, it is always driven at a constant speed to prevent unevenness.

The conventional servo control method for the robot 7 is executed as follows by the control device having the above configuration. Here, for the purpose of simplifying the description, the operation of the robot 7 is as follows.
Only one dimension (for example, the moving direction of the spray gun 7b is only the direction of the arrow in FIG. 5).

A control command for position correction is output from the CPU 1 to the servo control unit 3 at predetermined control cycles in accordance with the contents stored in the memory 2 as shown in FIG. Now, set the control cycle to 10
If the constant drive speed is 1 mm / msec (= 1 m / sec), the operation based on the stored contents in FIG. 6, that is, the time t (msec) after the start of the control and the position P (mm) of the spray gun 7b, Is as shown by a solid line 8 in FIG.

In other words, the control command output at the time point of 80 msec after the start of control reaches the point at the position of 83 mm and outputs a predetermined operation command (the above-mentioned "1"). The positioning time 83 msec for outputting the operation command and the like to the gun 7 b is the control command output time (10
(multiple of msec), and the next time the control command is output is at 90 msec. Therefore, as shown in FIG. 7, the robot 7 stops for 7 msec from 83 msec to 90 msec, and from the time of 90 msec, again keeps a constant speed of 1 mm / msec.
Move with.

At this time, since the stop time is extremely short (7 msec), the actual movement of the robot 7 may not stop due to the distortion of the servo system or the mechanical system, etc., and the speed may seem to change. You may not be able to see it.

Here, the slow acceleration processing time at the time of starting is irrelevant to the present invention and is ignored.

[Problems to be solved by the invention] However, in the conventional servo control method described above,
If a positioning time point for outputting an operation command or the like to the spray gun 7b for an on / off operation command (for example, an on / off command for spraying paint from the spray gun 7b) or the like is taught at a relatively short interval, this point Each time the vehicle passes through, a stop portion as shown in FIG. 7 is generated and the speed changes. In particular, when the moving speed is high, abnormal vibration may occur.

Therefore, if the motor is driven at a low speed so as not to cause abnormal vibration, the speed unevenness becomes remarkable this time, causing unevenness in the coating and the like, thereby lowering the work efficiency and the work quality.

The present invention is intended to solve these problems, and even when teaching at short intervals the positioning time for outputting an operation command or the like to the spray gun 7b, without stopping the operating part at the positioning time. It is an object of the present invention to provide a servo control method for a robot that enables high-speed drive control at a constant speed to improve work efficiency and work quality.

[Means for Solving the Problems] For this reason, the first robot servo control method of the present invention (described in claim 1) outputs an operation command or the like to an operation part taught in advance. It is determined whether there is a difference between the positioning time for performing and the control command output time for each predetermined control cycle, and if there is a difference,
When the operating part continues to move at a predetermined speed, a position reached at the next control command output time is calculated, and a positioning correction control command for moving the operating part to the same position at the predetermined speed is transmitted to the driving unit. The feature is to output to.

The second robot servo control method (described in claim 2) of the present invention includes a positioning time point and a predetermined control period for outputting an operation command or the like for the operation part taught in advance. It is determined whether or not there is a difference between each control command output time, and if there is a difference,
The present invention is characterized in that the positioning time is changed to a control command output time, and thereafter, the control command output time for each of the predetermined control cycles is set with the same positioning time as a starting point.

[Operation] In the first robot servo control method of the present invention described above, even if the positioning time point taught to output an operation command or the like to the operation part of the robot is different from the control command output time point, Since the positioning correction control command is output to the drive unit so as to move the operating part at a predetermined speed, the operating part continues to move at a constant speed without stopping at the time of the positioning as in the related art.

In the second robot servo control method of the present invention described above, even if the positioning time point taught to output an operation command or the like to the operation part of the robot is different from the control command output time point, a predetermined time is determined from that time point. Since the control command will be output every control cycle of the above, the operating part does not stop at the time of the positioning as in the related art,
Keep moving at a constant speed.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show a servo control system of a robot as a first embodiment of the present invention, and FIG. FIG. 2 is a graph for explaining the operation. Also in this first embodiment, the hardware used is the same as that shown in FIG. 5, a coating robot 7 is used as the robot, and the operation part is a spray gun.
7b, in the present embodiment, the control by the CPU 1 is executed according to the flowchart shown in FIG.

At the time of outputting the control command, first, it is determined whether or not the control command is a positioning point at which positioning for outputting an operation command or the like to the spray gun 7b taught in advance should be performed (step A1). At this time, if it is determined that the time is the positioning time, the speed of the spray gun 7b is always a constant v. Therefore, from the speed v and the moving distance L up to the positioning time, the current positioning time (movement is determined). The time required from the start until the current positioning time is reached) T
It is determined by L / v (step A2).

Then, the seeking remainder t _r by dividing the positioning time T at the control period τ determined (step A3), and determines whether the remainder t _r is zero (step A4). Here, the remainder _tr is 0
In this case, it can be determined that the positioning time T is a multiple of the control cycle τ and coincides with the control command output time for each control cycle τ, and the process returns to step A1 while the remainder _tr is not 0. It is determined that the positioning time T is different from the control command output time (a multiple of the control cycle τ), and the process proceeds to the next step A5.

In step A5, obtains the time t ₁ required from the positioning point T until the next control command output time as tau-t _r, determine the next control command output time T ₁ as T + t ₁ (see FIG. 2).

Incidentally, in the conventional control method, during the time t ₁ of the positioning point T and the next control command output time T _1, the spray gun 7b
In the control method according to the present embodiment, the spray gun 7b continues to move at the predetermined speed v. Therefore, when the spray gun 7b continues to move at the speed v without stopping, the time t _The distance l ₁ to move during ₁ is obtained by v · t ₁ , and the position L ₁ reached after the lapse of the time t _{1 is} obtained as L + l ₁ (step A6).

As the spray gun 7b to the next control command output time T ₁ (a multiple of the control period tau) reaches the position L _1, CPU 1
Outputs a positioning correction control command to the servo control unit 3 as a drive unit (step A7).

Thereafter, every time the positioning time comes, the same processing as described above is performed.

Next, a case where the control method of the present embodiment is applied to the specific conventional example shown in FIGS. 6 and 7 will be described while applying specific numerical values. Here, L = 83 mm, v = 1 mm /
msec, τ = 10 msec.
3 (mm) / 1 (mm / msec) = 83 (msec) (Step A2), 83 (msec) / 10 (msec) = 8 remainder 3 (mse)
c) is obtained (step A3). In addition, 83
(Msec) to the time t ₁ required to output the next control command
Is, 10 (msec) -3 (msec ) = 7 (msec) , and the next control command output time T ₁ is, 83 (msec) +7 (msec ) = 90
(Msec) (step A5). And spray gun
If 7b continues to move at a speed of 1 (mm / msec) without stopping, the distance l ₁ that moves during time 7 (msec) is 1
(Mm / msec) × 7 (msec) = 7 (mm), and 7 (mse
position L ₁ reached after c) elapsed, 83 (mm) +7 (mm ) = 9
It becomes 0 (mm) (step A6). So, in this example,
At the next control command output time 90 (msec), spray gun 7b
The CPU 1 outputs a positioning correction control command from the CPU 1 to the servo control unit 3 so that the position reaches 90 (mm).

As described above, according to the first embodiment of the present invention, the positioning time T taught in advance to output the operation command or the like to the robot 7 (spray gun 7b) is the control command output time (a multiple of the control cycle τ). ), A positioning correction control command is output from the CPU 1 to the servo control unit 3 so as to reach the predetermined position L ₁ at the control command output time T ₁ next to the positioning time T. Then, since the time difference is corrected, the spray gun 7b keeps moving at a constant speed without any stop at the positioning time T. Therefore, even when the positioning time for outputting the operation command or the like to the spray gun 7b is taught at a short interval, the spray gun 7b is not stopped at the positioning time, and no abnormal vibration occurs. Since the drive can be controlled at a high speed and at a constant speed, work efficiency and work quality are greatly improved.

In particular, in the case of the coating robot 7, the robot 7
Can be controlled by setting the positioning time at an arbitrary point and outputting an on / off operation command while operating at a high speed. Since the operation speed does not change, the on / off operation can be accurately performed.
An OFF operation command can be output, and positioning is possible. Masking work other than the position where spray coating is conventionally performed is unnecessary. In other words, the spray gun
By turning off the spray gun 7b and turning on the spray gun 7b at the part where the application is required, the application location can be freely controlled. Further, since the operation speed is constant, uniform work can be performed without causing unevenness at the application start point.

Next, a servo control method for a robot according to a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIGS. 3 and 4 show a servo control method for a robot according to a second embodiment of the present invention. FIG. 3 is a flowchart of the operation, and FIG. 4 is a graph for explaining the operation. In the second embodiment, the same hardware as that of the first embodiment is applied, but in this embodiment, the control by the CPU 1 is executed according to the flowchart shown in FIG. In FIG. 3, steps B1 to B4 are completely the same as steps A1 to A4 in the first embodiment shown in FIG. 1, and a description thereof will be omitted.

In the second embodiment, as shown in FIG.
In B4, it was determined that the residual _tr was not 0 and the positioning time T for outputting an operation command or the like to the spray gun 7b was different from the control command output time (a multiple of the control cycle τ). In this case, in step B5, the positioning time T is changed to the control command output time, and thereafter, the control command output time for each control cycle τ is set starting from the positioning time T. In other words, when the positioning time T deviates from the control command output time, the reference for setting the control command output time is changed to the positioning time T.

Thereafter, the same processing as described above is performed each time a positioning time point for outputting an operation command or the like to the spray gun 7b arrives.

The case where the control method of this embodiment is applied to a specific example (see FIG. 2) similar to that of the first embodiment will be described with reference to FIG. 3. In this second embodiment, the positioning time T is determined by the control command output. If it is determined that it is 83 msec different from the time point,
Immediately, the time of 83 msec becomes the control command output time, and thereafter, 93 msec, 103 msec, 113 msec,... In the control cycle τ become the control command output time. That is, for the next control command output time of 80 msec, the control cycle τ is temporarily changed from 10 msec.
It can be considered that the control command is shortened to 3 msec to 83 msec, and thereafter, a control command is output at a control cycle of 10 msec as usual.

As described above, according to the second embodiment of the present invention, the positioning time T taught in advance to output an operation command or the like to the robot 7 (spray gun 7b) is the control command output time (a multiple of the control cycle τ). ), A control command is output at every predetermined control period τ from the positioning time T, so that the spray gun 7b must be stopped at the positioning time T at all. And keep moving at a constant speed. Therefore, according to the present embodiment, it is possible to obtain exactly the same effects as in the first embodiment.

Although the first and second embodiments described above are directed to coating robots as robots, the control method of the present invention is not limited to this, and can be applied to various other robots. Is done.

[Effects of the Invention] As described above in detail, according to any of the first and second robot servo control methods of the present invention, the positioning of the operating part of the robot for outputting an operation command or the like to the operating part is performed. Since the drive can be controlled so as to keep moving at a constant speed without stopping at any point in time, even if the positioning point for outputting the operation command is taught at a short interval, the operating part is Can be controlled at a high speed and at a constant speed without stopping the motor and without generating abnormal vibration, and there is an effect that work efficiency and work quality are greatly improved.

[Brief description of the drawings]

FIGS. 1 and 2 show a servo control system of a robot as a first embodiment of the present invention. FIG. 1 is a flowchart thereof, FIG. 2 is a graph for explaining the operation thereof, and FIGS.
FIG. 3 shows a robot servo control system according to a first embodiment of the present invention, and FIG.
FIG. 5 is a graph for explaining the operation, FIG. 5 is a block diagram schematically showing a control device of a general coating robot, and FIG. 6 is a specific example stored in a memory of the control device. FIG. 7 is a graph for explaining a conventional robot servo control system. In the figure, 1 ... CPU, 2 ... Memory, 3 ... Servo control unit, 4 ... I / O interface unit, 5 ... Operation switch interface unit, 6 ... Teaching board, 7 ... Coating robot, 7a …… Arm, 7b …… Spray gun as an operating part.

Claims (2)

(57) [Claims] 1. A servo control method for a robot, which outputs a control command to a drive section of an operation part of a robot at a predetermined control cycle to perform positioning control of the operation part and constant-speed drive control at a predetermined speed. At the time of positioning for outputting an operation command or the like to the above-mentioned operation part taught, it is determined whether or not there is a difference between the positioning time and the control command output time for each predetermined cycle. If it is determined that the operating part has continued to move at the predetermined speed even after the positioning, the position reached at the next control command output time is calculated, and the operating part is moved to the calculated position. A servo control method for a robot, wherein a stop time of the operating part is eliminated by outputting a positioning correction command for moving at a predetermined speed to the drive unit. 2. A robot servo control method according to claim 1, wherein a control command is output to a drive unit of the robot at a predetermined control cycle, and the positioning control of the motion unit and the constant speed drive control at a predetermined speed are performed. At the time of positioning for outputting an operation command or the like to the above-mentioned operation part taught, it is determined whether or not there is a difference between the positioning time and the control command output time for each predetermined cycle. When it is determined that the operation has been performed, the positioning time is changed to the control command output time, and thereafter, the control command output time for each of the predetermined control cycles is set with the same positioning time as a starting point, whereby the operation is performed. A servo control method for a robot, wherein a stop time of a part is eliminated.